function Hv = H( alpha, beta )

k = [cos(alpha)*cos(beta); % Unit vector
cos(alpha)*sin(beta);
sin(alpha)];
r{1} = [1/8 0 0]; % Antenna's radius-vector, lambdas
r{2} = [-1/8 0 0];
phi = nan(2,1);
for i = 1:2
phi(i) = 2*pi * r{i} * k;
end
Hv = exp( 1i * phi );
end